TOPIC:

I think this could be used to convert a chain drive Optima to belt drive. Can anyone confirm this?

Martin, you are correct. The belt drive conversion was the hop-up of choice for racers of these buggies in the day. It was a lot quieter, lower maintenance, more reliable and smoother power transmission. The belts and diffs are not to scares but, can be pricy. Your lot should bring a good number.
Marius